Recently emerging technologies in recording media, spintronics, imaging, and sensors, have driven a need for nanometer-scale magnetic materials and devices and methods for making them. Nanometer-scale magnetic building blocks are typically used to fabricate such magnetic nanostructures. Recently, considerable efforts have been made in the area of self-assembling magnetic nanostructures. For example, three-dimensional assemblies of magnetic nanocrystals have been extensively investigated in order to apply them as building blocks in magnetic devices, where the control of the size, shape, and morphology of the nanocrystals is critical for the suitable catalytic, optical, and magnetic properties. One of the important classes of building block structures is a magnetic nanowire. Synthetic magnetic nanowires have been produced; however, the ability to tune the magnetic properties of these nanowires has proven to be difficult.
In addition, magnetic particles are used commercially for cell separation. Typical commercial magnetic particles are paramagnetic, however, and on the order of micrometers in diameter. Smaller magnetic particles are desired for applications such as biosensors, magnetic separation, biological assays, and enzyme substrate. The use of smaller particles increases the efficiency of cell separation, for example, due simply to the resultant increased surface area. The synthetic manufacture of the desired nanometer-sized magnetic particles for these applications is difficult, however, because such tiny particles are extremely difficult to collect, even with the use of magnetic fields, due to their characteristically weak magnetic moments.
There exists a need, therefore, which is lacking, in the prior art, for magnetic nanometer-sized particles and nanotubes of greater magnetic field strength than currently available. There also exists a need for new methods of fabricating magnetic nanotubes, which allow for tunability of their magnetic properties.